[TerryO]

I've heard a number of Kevin's, I mean Mr. Haskin's, speakers and have always thought that he made intelligent choices when it came to his designs. There are many (some quite well known) that don't, at least in my opinion.

Best Regards,
TerryO

Well thank you Mr. Olsen.     A lot of it comes down to personal choice based upon listening so we have not yet removed the art of loudspeaker design into the realm of a pure science.    There is a final judgment of the sound that is a purely subjective call to decide upon the final voicing.    It helps to understand the mechanisms involved to make intelligent design choices though.   

I think your going to like the dipole.   Once I get the DPL-10s in place I'll let you take a pair to the NW Audio Society meeting.   I see that your writing articles about speaker design for the club newsletter.    Oh boy....

Jeez, I hit the return and posted this without getting a chance to actually write anything. So I'm "modifying" this to include my text.

Concerning the Dipoles, as soon as you get a fix on the design and can get one ready, I'd be honored to introduce the design to the Pacific Northwest Audio Society (PNWAS). The truth is that very few of the members have probably ever heard a properly designed dipole and, in fact, may never have heard *ANY* dipole design. I would ask that you include one of your amplifiers as the Club's listening area is rather large and the 60 watts per channel club amp may not supply the headroom to demonstrate your design to best effect. That and a set of your splendid cables should allow the dipoles to be presented as well as the clubs room will allow.

The rather basic articles that I'm submitting to the Club is to generate some understanding as to speaker design and hopefully to encourage some of the members to try their hand at it. I fully believe that through experience comes understanding, and if nothing else it makes one appreciate what goes into a successful design. It's a well known fact that, if one's first effort at speakerbuilding even remotely sounds like music, the individual's Auditory Nerologic Nexis will supplement or offset any deficiencies thus resulting in an entirely superb performance.

Best Regards,
TerryO

[guest1632]

Some measurements...

A couple notes... these may change slightly.   I've done about 5-6 crossover revisions and these where built with parts I had on hand.   For the production version I'm planning on using Erse Super Q inductors which have a much lower DCR and will bring the EX-6.5 output up some.   I'll adjust as needed but these graphs have a higher frequency tilt that will not be so exaggerated in the production version.

The crossover is around 1.6K which is low for a typical 1" dome tweeter.   No problems with this Peerless unit though.   Distortion testing (THD, IMD) in the final version to confirm.   Crossing over this low has the advantage of having smoother response off-axis.   The midwoofer begins to beam at a much lower frequency than the tweeter so crossing over to it low, where the dispersion is wide (relative), keeps the off axis from having a large narrowing pattern near the crossover frequency.   Its harder on the tweeter so you need a good tweet, good crossover design & then you need to measure distortion in the final design to confirm that you get it right.

The dip @ 3K & 6.5K are baffle diffraction related dips and their effects are negligible off-axis.    The peak @ 15K is in the tweeter response and remains to some degree in all the measurements.   



Here is about 15 deg off-axis.   The upper frequency tilt starts to come down a little and you see the beginning of the tweeter roll-off.   The broad peak around 2-4K is a work in progress.   I may allow an on-axis dip in the final response to get this smoother off-axis.    This area is what sounds forward or "bright" in a loudspeaker design.   Its not the >10K.   Brightness is typically due to a problem in the 2K-5K range.   



Here is the 30deg off-axis.



And this is >45deg.   Notice the crossover notch starts to show.   The woofer's dispersion pattern is narrowing relative to the tweeter at this extreme off-axis position. 



Here is the reverse null.   This is 1/6th smoothed so the bottom of the null has been filled.   The baffle step showed up more in this measurement.   I've done about 4db of compensation leaving 2db for room reinforcement.



Here is the waterfall.   The waterfall is useful to check for any resonance issues in the final design.    I look for everything above 1K to die off >40db down within the first 2ms.      If you get up around 4-5ms things start to become audible but it also shows up in the FR on-axis or off.   This is just another way of checking for FR issues and you can see my broad 2K-4K peak in the waterfall showing up even though it wasn't in the on-axis response.   

Overall though.... this is much better than you see in typical designs that do  a simple on-axis measurement, optimize for smooth response and call it done.    This represents a LOT of measurement, model, build, measure, tweak, measure, tweak, measure, tweak, measure, listen, tweak, measure, listen, tweak, measure, listen design cycles.   You get the idea.     

Hi Kevin,

So the impression that I am getting is that the speakers will have a more forward sound say up in the 800 to say 1200 HZ a bit more forwardness? What do you perceive the sound character of the speaker to be in its final stages? So if forward, what will the image be like, ... behind the speakers, or in front?

 Ray

[Kevin Haskins]

I'm not yet ready to finalize the design.   I've got some more parts coming for another crossover revision.    After I'm 100% done with the design I'd be happy to give a general subjective impression.    Better yet... I'd like to offer a demo tour so that I can get some feedback from other systems and people.

I've been working on the PCB design for the active version.   I'd like to have some proto boards for the active design before the end of the year.   The cool thing is that all the Anadigm enabled functions that we have been working on for the Woofer Widget will be implimented into our active loudspeaker designs.   That means tools for room equilization and room measurement capabilities with the active speaker kits.    Imagine a fully active loudspeaker kit, with programmable EQ settings to EQ the bass, Linkwitz transform to extend the bottom-end etc...       

[TerryO]

Kevin,
This is slightly off-topic, but I couldn't help but notice that you've just hit 1000 posts. Welcome to the Millennium Club!
Best Regards,
TerryO

[Kevin Haskins]

Thanks for pointing that out Terry.   I'm going to stop at this number.... maybe 1001 because that is a special number for me. 

[Kevin Haskins]

El Fin....    I'm done with the design.    PCBs & crossover parts are on order.    I'll post some final measurements when I get all the crossover parts in stock.    Final design looks to be +/- 0.5db to the baffle step and stays very smooth off-axis.   

Final pricing is going to be $299 per speaker which includes everything but the cabinet.    The crossovers are on PCBs and assembled so there is no crossover assembly to be done.   If you want the finished cabinets there is some good news.  There is a new "curved side" cabinet that looks very nice.   The standard Parts Express rectangular cabinet is $75 each and the new curved wall model, which looks to be completely interchangable for the Kepler is $95 each.    For $20 the curved wall cabinet also has magnetic grills so its a pretty cool option.    I'll buy and confirm that the curved-wall version works but since the front baffle is the same, I doubt there will be much of a difference in the finished cabinet.   

Overall good timing though... those curved wall cabinets look pretty sexy.   Figure $750-$800/pr for some state of the art montors.   

Upgrades?   I'm not going to suggest any passive crossover upgrades.   I'm working on the active parts now and an active version should be available sometime next year.    The active version brings more than just a typical active design.   It will offer room measurement & with bass EQ, time alignment of the drivers, bass extension, and a sophisticated limiting function for the loudspeaker that will adjust dynamically with drive level and frequency all done in the analog domain.    In other words... it offers features not availabe in ANY other loudspeaker on the planet.... at any price.